Abstract: An electret includes an electret layer. The electret layer is formed by subjecting a composite film in which inorganic dielectric particles are dispersed and held in a base film to a polarization treatment. The inorganic dielectric particles are mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more.

Abstract: An electret includes an electret layer. The electret layer is formed by subjecting a composite film in which inorganic dielectric particles are dispersed and held in a base film to a polarization treatment. The inorganic dielectric particles are mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more.

Abstract: End-mill machining control method and apparatus in which cutting forces tangential and normal to tool motion are detected and machining is controlled based on the detected cutting force values. A primary component Ft and motion axis components Fx, Fy of a cutting force are determined from current values of a spindle motor and motion axis motors for tool feed. A cutting-engaged angle ?en is determined from a radius R of a tool and a depth of cut I into a workpiece. A motion direction angle ? is determined from distribution motion amounts ?X, ?Y to the axes. The cutting forces Fm, Fs tangential and normal to tool motion are determined from the primary component Ft and a motion axis component Fx or Fy whichever is the largest, the cutting-engaged angle ?en, the motion direction angle ?. The accuracy of the determined cutting forces Fm, Fs is high since they are determined from the primary component Ft less affected by disturbance and the largest axis component of the cutting force.

Abstract: End-mill machining control method and apparatus in which cutting forces tangential and normal to tool motion are detected and machining is controlled based on the detected cutting force values. A primary component Ft and motion axis components Fx, Fy of a cutting force are determined from current values of a spindle motor and motion axis motors for tool feed. A cutting-engaged angle &agr;en is determined from a radius R of a tool and a depth of cut I into a workpiece. A motion direction angle &bgr; is determined from distribution motion amounts &Dgr;X, &Dgr;Y to the axes. The cutting forces Fm, Fs tangential and normal to tool motion are determined from the primary component Ft and a motion axis component Fx or Fy whichever is the largest, the cutting-engaged angle &agr;en, the motion direction angle &bgr;. The accuracy of the determined cutting forces Fm, Fs is high since they are determined from the primary component Ft less affected by disturbance and the largest axis component of the cutting force.